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Old 11-08-2011, 04:51 AM   #1
Merp
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Patches on OEM ECU

Default Open Source Speed Density Patches

Hey guys, just wanted to give you a heads up, I am working on speed density patches for 32bit ecu's.

The 06/07 USDM WRX MT rom is currently the only rom available, but STi roms are in the works. I will update this thread as they roll out.

To request a particular rom to be patched, send me a pm or donation through the link.

RomRaider • View topic - Speed Density ROM - A8DH201X 2006/2007 WRX

Thanks!
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Old 11-08-2011, 09:54 AM   #2
aeonflux99
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Awesome!
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Old 11-10-2011, 02:39 PM   #3
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What's the difference between speed density tuning and mass airflow tuning? Does anyone have any good links on the topic? In other words why would you want to change to speed density tuning?
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Old 11-10-2011, 03:10 PM   #4
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MAF tuning is finnicky when you start to get away from stock intake size, not only that but you can't upgrade your MAF sensor, hence you start to get to the point that you are maxing out the sensor and can't make any more power because of that. Not only that but with high horsepower maf cars daily driveability suffers, where a speed density tuned car can just go up to a larger map sensor and still have near the same amount of driveability.
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Old 11-10-2011, 05:57 PM   #5
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Can you still pass emissions once running speed density?
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Old 11-10-2011, 06:01 PM   #6
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at what point does the factory maf tap out? Since this is about open source tuning using the factory ecu, would you pass emissions switching to speed density?
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Old 11-10-2011, 06:05 PM   #7
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At what point does the factory maf tap out? Since this is about open source tuning using the factory ecu, would you pass emissions switching to speed density?

found a good link on the subject i believe:

http://ls1tech.com/forums/pcm-diagno...d-density.html
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Old 11-10-2011, 06:27 PM   #8
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I've never maxed a factory, but my old APS 70mm (stock is 65mm) was getting very close around 400whp.

This speed density simply replicates the MAF output using an algorithm, when tuned properly, it will pass emissions.
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Old 11-11-2011, 03:34 PM   #9
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Very nice, I will give this a shot. As far as maxing the maf goes, I am just at the point of maxing mine on my 07 wrx with an aps 65mm intake, gimmick inlet and aftermaf, vf39, and catless tbe. When it gets cold, I am hitting 4.7 volts. The maf table max shows 4.69 volts.
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Old 12-18-2011, 04:21 PM   #10
mecpgh
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Bump for this thread. Ready to test one for 05sti rom but I'm no software engineer. Hoping you guys are going to do patches because I'm site I would have no trouble selling it with my tunes locally.
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Old 12-19-2011, 04:37 PM   #11
aeonflux99
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APS 70mm intake and it's showing a peak of 4.59 volts. So I might be very interested in giving this a try as well. That said my daily drivability is still pretty decent, despite how much AF learning at idle I end up with.
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Old 12-19-2011, 05:31 PM   #12
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There are advantages and disadvantages to each system.

Speed density systems tend to be a little better for higher powered cars where large maf housings would otherwise be needed. With the larger maf housing there is always a sacrifice of resolution and consistency. Speed density is almost required for most rotated turbo systems since they cause a lot of turbulence at the maf. Also Atmospheric BOV's can be used without any negative effects. And things like Boost leaks will not change your AFR's.
For a speed density car, any mod that helps flow more efficiently like headers or exhaust will change the VE and the car will need to be retuned. Even something as small as changing out the exhaust could potentially cause issues. In these circumstances a freer flowing modification (adding a dp) will cause the car to run rich and a restrictive change (adding a cat) will cause the car to run lean.
Many speed density systems do not handle atmospheric pressure changes well so if you regularly drive up and down in large elevations then you will not get the best performance out of the car. A nice standalone with MAP/(Barometric pressure) system for determining VE is probably necessary. A system like this one or Cobb's Speed density(available via protune) is not up to this task.

The advantage to MAF is that it takes VE completely out of the equation so it handles elevation changes better as well as mods(other than the intake system), without needing to be retuned as thoroughly. Changing out exhaust, cams, intake manifold and turbos should not effect the AFR's as the increase in airflow or VE is measured at the MAF and accounted for as long as the car is properly tuned.

The move to a speed density system of any kind(reflash or standalone) is a decision you will have to weigh carefully for your needs. For most people if you aren't having issues with your MAF based tune the move to speed density is not really needed.
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Old 12-19-2011, 10:27 PM   #13
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Quote:
Originally Posted by eminehart View Post
A nice standalone with MAP/(Barometric pressure) system for determining VE is probably necessary. A system like this one or Cobb's Speed density(available via protune) is not up to this task.
It would not be too hard to add a barometric pressure compensation to the open source speed density patches. Is 4000 feet of elevation change enough to make a measurable difference in AFR? If so I'll be able to study this in a couple weeks when I get SD on my car and go snowboarding. If you have a rough idea of how much that should change the mixture, that would be helpful.

Thanks!
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